Circuit breakers of this type interrupt the current by creating and extinguishing the arc in a vacuum container. Vacuum circuit breakers have been developed to have a longer live expectancy than air circuit breakers. A vacuum circuit breaker includes one electrical pole per phase, wherein each pole part includes an interrupter chamber, which can be a vacuum interrupter or a chamber filled with SF6 or oil. Further, the poles include a drive rod for operating a movable electrical contact of the pair of electrical contacts, where the drive rod is accommodated inside the interrupter chamber. Circuit breakers of the present disclosure are used in the field of medium—voltage to high—voltage applications.
EP 0 817 225 A1 discloses a medium-voltage circuit breaker arrangement with three pole parts mounted on a common mounting surface of a housing for accommodating drive means for synchronously operating the moveable electrical contact of each pole part.
Each pole part contains a pair of electrical contacts which are a arranged inside of a switching chamber insulator, which is supported on a mechanism chasing attached to the box-type housing.
A pivot shaft running transverse to the switching direction is arranged in each mechanism chasing of each pole part, penetrating the mechanism chasing and the housing. A rocker arm is fixedly secured to that part of the shaft running inside of the mechanism chasing, and is connected to the moveable electrical contact by an insulating rod arranged as a pushrod. The pushrod is articulated to the rocker arm at one end and the moveable electrical contact on the other end. All shafts are on a common level and are parallel to each other. The pivot angle of the rocker arms is generally within an angular arrangement of 50° to 130°. Both end-point positions of the rocker arms correspond to the off position of the circuit breaker. The part of each shaft within the housing has a bifurcated rocker link, both arms of which are provided with a slot running radially relative to the shaft access. A respective lever, also arranged in the housing, is provided for other services of the arms. These auxiliary levers are parallel to each other and are connected to each other by a rod or a bolt, protruding through the slots of the bifurcated rocker link, thereby forming a crank-type structure.
The rod or bolt of the center pole part is linked by a respective coupler to the bolt of the other pole parts. A drive coupler is articulated to the bolt of the interrupter unit, and is linked to one end to the driver lever. The driver lever is situated on a drive shaft of a common actuator unit. The transmission means for transferring the switching force from the actuator unit to each pole part is based on a drawbar principle. The drawbar runs from the common drive unit along the housing and is connected to each pole part as described above. Many single parts are necessary on the transmission part.
U.S. Pat. No. 3,806,684 discloses a special transmission mechanism for converting a hand-operated circuit breaker to a motor-operated circuit breaker.
The circuit breaker including a metallic housing structure and a circuit breaker mechanism is supported on the housing structure. The housing structure includes a base plate and a pair of side plates connected to the base plate with a pair of spaced generally parallel center plates.
A crank shaft is supported on these center plates with a closing cam supported on the crank shaft between the center plates. A pair of springs is connected to the crank shaft, at the opposed sites of the center plates, to provide suitable energy means for closing the circuit breaker contacts.
A jack shaft that is common to all of the pole parts and pivotally moveable to operate the moveable contacts for all of the pole parts is supported at the opposite ends thereof in bearings mounted on the site plats. The bearings on the center plates are open at one site to permit movement of the jack shaft into the open center plate bearings to provide assembly of the circuit breaker. A link that is supported on the site of the center plates engages a trip bar to ledge the circuit breaker in the reset operating position. Ledgering forces act on the trip bar in proximity to center plate.
The closing cam includes twin cam members with a roller ledge supported between the twin cam members. A closing ledge engages the roller ledge to hold the closing cam in the charged position until it is desired to close the circuit breaker. Thereupon, the closing ledge is operated to release the roller and the start energy of the closing springs services to operate the crank to thereby operate the jack shaft to close the electrical contacts.
Due to the double-function of the disclosed technical solution, the transmission means for transferring the switching force to each pole part have a complex design. However, the transmission means are based on a rotation principal of a common jack shaft, on which lever arms are attached for operating the pushrods of each pole part.